UPSC NCERT study: how to separate essential points from trivial detail

Reviewing the UPSC syllabus and question papers, I find the material quite perplexing. I am struggling to differentiate between essential information and trivial details within the NCERT textbooks. I request assistance in identifying which points to highlight and which to overlook to streamline my preparation. ....(⁠ ⁠◜⁠‿⁠◝⁠ ⁠)